Sulphurized oil



Patented June ll, lgdfi 2,2llth53d SUWHTURIEIED lllllia ldert ill. Lincoln and Waldo L. Steiner, Ponca Bity, @hlat, assignors to @ontinental Oil Company, llonca (City, illrla, a corporation of Delaware l lo lllrawina'. duplication March Serial N0. M588 1 iglaim.

Our invention relates to sulphurized oils and new compositions of matter used in the preparation thereof. 1

It has long been known that sulphur compounds when added to lubricating oils impart certain properties to the mixtures which are of great value when these mixtures are used as lubricants for very'heavy duty such as is en. countered in the lubrication of automotive gears of the hypoid and spiral bevel types and other power transmission gears and for the lubrication of cutting tools such as are used in cutting and threading steel pipe. The exact manner in while the sulphur compounds, with respect to the on than a matter of theincreased film strength which sulphur compounds impart to lubricating oils since for each sulphur compound that'may be added to a lubricating oil to increase its film strength, there is an optimum percentage above which there is no tendency to obtain further increase with greater percentages of the sulphur compound. On the other hand there seems to be no limit to the improvement of a cutting oil that can be obtained by increasing its sulphur content, at least as far as thesmoothness otth metal cut obtained with it is concerned. 3

All sulphur compounds do not have this beneficial elfect on lubricants to the same degree as will be brought out in the examples given herev inbelow and to most of. those now in use, there are certain definite objections. The most coinmon sulphur compounds used for blending with 5 lubricating oils are the sulphuretted glyccrides of the unsaturated fatty acids. These usually cone tain about 12% sulphur. Sluphurettedlard oil is a typical example. These compounds are not entirely satisfactory for blending purposes. for

sulphur base oils, cutting lubricants are obtained which are rather inefllcient as far as out ting qualities are concerned, objectionable on account of odor, irritating to the skin of the 0p terator and in case oi slight cuts on the hand,

ting lubricants, act fi 'oduce these resultsis no known with any ree of certainty. Itismcre" several reasons. The sulphuretted clycerides are Even with using a large percentage of these.

(CB. fillil) cause sores difficult to heal, are very viscous when cold, and are not stable to heat while in use, as they break down and thin out.

An extreme pressure lubricant for gears which is made from the conventional sulphuretted 15*. glycerides, such as for example lard oil, has many defects. In the first place, this type sul" phur base blend is not as stable as is desired to the copper strip corrosion test, which some autm mobile manufacturers now require for sulphur base lubricants. Secondly, the film strength is not very high, and last, the pour point of the lubricant is raised 5 degrees to 25 do pending upon the type 1 used i We have discovered t monohydric and dihydric-alcuh v acids make excellent stuplilu'r ha y ing with lubricants for preparingsuperior cut ting oils and gear lubricants..- .FZIhey-iare so; or so to the conventional sulphuretted glyceridcs oi, un-- saturated fatty acids in a number of ways. To begin with they are inaencral much less viscous even when containing a much larger percentage oi sulphur and are therefore easier to h my heylmay be easily and nertiaariei ti messes a2 tyne-vats? tiliil'iiiie i.

*" 'Yew minutes-"with an I phurettin g. They are, a ia iii-cup, stable to heat than the sulphuretted glycerides g-m and consequently, do not break down and thin out in service as readily. When the glyceride breaths down glycerine is released which forms grim and "is generally objectionable. They do not irritate the skin of the operators. They are cheaper he Mi cause about twice as much sulphur may be added to this type of compound as can be added to the gly'cerides and thus give a more concentrated base oil. Another important advantage of these ,sulphuretted rnonchydric and dihydric alcohol esters is that they are more soluble in petroleum lubricants than the sulphLu-etted glycerldes. The latter have a marked tendency to show a sludge-like deposit on the bottom of the container in which a blend of this base and a petroleum my lubricant has stood for some time. Lastly, the" pour point of blends made with a petroleum lu bricant are higher by 10 degrees to 25 degrees ll. (depending on the type of lubricant) when a ,sul-= phurettecl glyceride is used than when a. sai phuretted monohydric alcohol ester is used.

The viscosity of the sulphuretted glycerlde blends is very much higher at temperatures from 0 degrees to degrees F. than the same blend where the sulphuric-tied inonohydric alcohol esters-of the same acids are used. This is a' conditions the machines do poor work and the cutting 'tools are dulled. The disadvantages of to a high pour test and high viscosity at cold weather temperatures in the case of gear lubricants causes excess loss of power in overcoming the internal friction of the lubricant and difficulty in shifting of gears in the case of auto- 15 mobile transmission gears.

, A number of examples of the sulphuretted ester type of blends for heavy duty lubricants is listed below'for the purpose of illustrating this invention.

Example No. l.-Commercially pure methyl oleate was heated to 380 degrees F. and sulphur was slowly added with stirring. After sufiicient sulphur had been added to give a compound containing 20% of sulphur, the temperature was 5 raised to 420 degrees F. and about 6% more of sulphur was taken up by the ester. The product was blown with sulphur dioxide at 380 degrees F.

for two minutes to remove hydrogen sulphide. On cooling, the ester was found to be much less so viscous than the glyceride after sulphurettlng. The glyceride cannot be made to take up more than 12% or 13% of. sulphur and cannot be heated to so high a temperature without breaking down. The sulphuretted ester, on blending with 5 a 100 S. S. U. viscosity black oil to the extent so that 2% of sulphur (equal to 8% of. the sulphur base) is added to the petroleum base, gives a superior cutting lubricant which is very stable to heat, flows readily at -14 degrees F., does not so thin out with use, has practically no odor, does not irritate the skin of the operator, and when used witha cutting machine gives a very smooth out. The same type of cutting oil made with the sulphuretted glyceride in which enough of the g5 sulphuretted glyceride (16% sulphuretted lard oil and 84% of the same black oil) is used to give the same amount of added sulphur has a very obnoxious odor due to hydrogen sulphide that is released, has a tendency to thin out more readily 60 in use, probably because it is less stable to heat, is thicker when cold having a pour point of 15 degrees 5 and gives a rougher machined surface when used with a cutting machine which in turn means a quicker dulling of the cutting tool, and 55 is extremely irritating to the skin. A cutting oil made'with the same viscosity black oil and sumcient sulphuretted methyl oleate to impart 4% or 5% of added sulphur (equal to 16% or 20% of. the sulphur base) gave a most extraordinarily efflcient cutting lubricant. When such a blend is used with a thread cutting machine a thread of almost velvety smoothness is obtained.

Ezmmple No. 2.--Commercially pure ethyl abietate was heated to 370 degrees F. and sulphur 65 was slowly added with stirring and raising of the temperature to 400 degrees F. until a product was obtained containing 27% sulphur. This sulphur base, blended with a 100 S. S. U. viscosity black oil to the extent that of sulphur (equal to m about 20% of sulphur base) is added to the blend,

gave an excellent cutting oil which was practically odorless and which had a very low cold test and flowed readily at 0 degrees F. It was stable to heat and did not thin out in use, and did not irritate the hands of the operator.

aeoaesa Example No. 3.-RfOSiI1 oil which is a mixture of aromatic acids similar to abietic acid was esterifled with methyl alcohol and the methyl esters sulphuretted by heating to 380 degrees F. and slowly stirring in sulphur until a compound con 5 taining 25% of sulphur was obtained. This sulphur base when blended with a 100 S. S. U. viscosity black'oil to the extent that about 4% of sulphur (equal to 16% of sulphur base) was added to the blend, made an economical and very effi cient cutting oil.

Example No. 4.-A mixture of, organic acids obtained as a by-product from pine wood processing and which consists of about 30% of rosin acids, 50% unsaturated fatty acids, and 20% of higher alcohols of the sterol type was esterified in the usual manner by refluxing with an excess of methyl alcohol using hydrochloric acid as a catalyst and the methyl esters and higher molecular weight esters thus resulting were then sulphuretted by heating to 380 to 400 degrees F. and by slowly adding sulphur with stirring. When the product contained'25% sulphur the temperature was dropped to 375 degrees F. and sulphur dioxide was blown into the compound for two minutes to remove excess hydrogen sulphide and to stabilize it. Air blowing for one minute then removed the excess of sulphur dioxide. Blends were made with 100 S. S. U. viscosity black oil containing 2%, 4%, and 6% of added sulphur. This required 8%, 16% and 24% respectively of sulphur base. These blends were tested for their efficiency as cutting oils by cutting threads under a standard set of operating conditions on a Toledo 2 thread cutting machine and comparing the threads thus obtained with threads cut with an expensive competitive cutting oil. The blend containing 2% of sulphur gave a thread slightly inferior to the competitive cutting oil but the 4% blend gave a thread which was its equal and the 6% blend gave a much superior thread.

These blends all gave threads that were far superior in evenness and smoothness to the threads obtained when sulphuretted lard oil was used in the lubricant even though as much as 30% of the sulphuretted lard oil was contained in the lubricant. In addition, they were quite free of. all odor and during a period of several weeks use did not in any way prove irritating to the skin of the operators. On cold mornings there was no difiiculty encountered in obtaining a good flow of lubricant in contrast to the viscousness of the sulphuretted lard oil blends under the same conditions. There also appeared to be no tendency towards breaking down and thinning out of the lubricant after a long period of use as was the case with the sulphuretted lard oil blends. The quality of the threads obtained after a long period of use for the oil was as high as when the oil was fresh.

The quality of thread is judged by the smoothness of the ridges and the lack of any pulling of the metal in the troughs.

Example N0. 5.A transmission gear lubricant prepared by blending 8% of the sulphuretted methyl oleate (equal to 1.6% of added sulphur) of Example No. l with 13% of 220 pale oil and 77% of steam refined stock gave an excellent extreme pressure lubricant. This lubricant had a film strength of 33 lbs. on'the Timken machine which is a standard testing machine for measuring film strength. This is equalto approximately 23,000 lbs. per square inch of rubbing surface. A transmission gear lubricant prepared by blending 13% of sulphuretted lard oil (equal to 1.6% 15 added sulphur) with 12% of 220 pale oil and 75% of steam refined stock gave a dim strength of 27 lbs. on the 'Ilmken machine. This is equal to about 19,100 lbs. per square inch. The odor of the former blend was pleasing while the latter smelled of hydrogen sulphide. A copper strip corrosion test at 210 degrees F. for one hour gave much less discoloration with the former lubricant than with the latter.

w Monohydric esters of the highly unsaturated fatty acids such as are found in fish oils cannot be readily sulphuretted so that an oil soluble derivative is obtained, but if the fish oil or esters therefrom are first partially hydrogenated, a

very satisfactory sulphur base for cutting oils can be gnade from them.

While examples of esters of methyl and ethyl and the high molecular weight alcohols in the pine wood acids of Example No. 4 only are cited,

80 it is to be remembered that other monohydric alcohols such as propyl, butyl, and higher alcohols can also be used for preparing the esters which are to be sulphuretted. Furthermore, the esters oi dihydric alcohols such as glycol mono or di-oleate might also be used with satisfactory results. Naturally occurring mono and dihydric esters may be employed in this invention.

The esters of the saturated fatty acids may also be sulphuretted and used in this invention. to It is necessary to use somewhat higher temperatures (400 degrees to 425 degrees F.) to sulphuret I nearly as much sulphur (usually only about 10%) I and have a. relatively high pour point. 40 A Any means of removing hydrogen sulphide from the sulphur bases after sulphurettingmay be employed. This may require the use of a weak oxidizing or reducing agent or treatment with gaseous sulphur dioxideas described in Example 4 No. 4 or any other means that gives satisfactory results. The means for the-removal of hydro- -gen sulphide irom the sulphur bases, however,

arenotapartoithisinvention.

While no specinc limits to the percentage of the sulphur to be used in preparing the different lubricants referred to in the examples has been drawn, it may be stated that in preparing a cutting oil to be used without first diluting, not s less than 1% or more than 4 %"oi added sulphur in the format the sulphur base in question is required. If a' cutting oil concentrate is prepared that is to be diluted before use, a much higher percentage of sulphur may be used in the m blend. The straight sulphuretted ester may be 7 used also for this purpose. or

In the case 01' preparing a lubricant for Q duty gears as little as .5% oi added sulphurfi" may be used for the mild extreme pressure lubricf" ant up to 2.5% of added sulphur for the more rugged extreme pressure lubricant. seldom necessary- "A small quantity such as .1% to .2% of sulphur in the term of one of these sulphur bases may be no added to a crank case lubricant to improve the film strength and oiliness of these lubricants.

The above ratios of sulphur base to petroleum oil for its diflerent uses are not intended to limit the scope oi this invention since smaller or larger quantities may be used in any case with results. which are partiallysatisfactory. They are givenbecause generally peaking the optimum'results can be obtained by using the ratios within the limits that are suggested. so

The hydrocarbon oils which are used in blending with the sulphuretted ester bases for the, preparation or the various sulphuretted lubricants, are not to-be limited to the hydrocarbon oils cited in the examples but are to include any- 86 hydrocarbon oil 0! any type or viscosity such as may be required by the lubricant in question.

Having thus described our invention, whatwe "claim is:

A lubricating 011 comprising in combination a major proportion of a hydrocarbon oil and a minor proportion of the sulphurized esters obtamed by esterii'ying with a monohydric or dihydric alcohol the fatty acids obtained from processing pine wood, and then sulphurizing these 45 esters.

BERT H. LINCOLN.

WALDO L. STEINER.

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